The unique epicuticular chemistry of Collembola – A cross-species analysis

Summary Springtails (Collembola), tiny hexapod arthropods, are abundant in the soil of most ecosystems, but our knowledge of their secondary metabolites is limited, in contrast to that of insects. In insects, the outer cuticle is usually covered by mixtures of long-chain hydrocarbons serving different functions, such as water regulation or chemical communication. In contrast, the knowledge of the epicuticular chemistry of springtails is scarce. We analyzed the cuticular lipids of 23 species covering different lineages. The often complicated structures were elucidated using gas chromatography/mass spectrometry, microderivatization, and synthesis. In contrast to insects, the terpene biosynthetic pathway is used for many of these lipids, producing unprecedented higher terpenes. In addition, evidence for de novo cholesterol biosynthesis in springtails was found, which is absent in insects. Finally, diverse non-insect linear compounds originating from the fatty acid biosynthetic pathway were identified. Our comparative analysis showed clear differences compared to insects and shed light on phylogenetic relationships.


1
Table S1.Overview of the compounds found in extracts of 23 Springtail species.Major components of the lipids of a species are shown in bold, except in species with only minor amounts of lipids.sq = squalene (10), ch = cholesterol, desmo = desmosterol.Long-chain alkanes and alkenes are described by their total carbon number, e.g.C20 for eicosane, related to Figure 4.

Figure S23 ..Figure S24 .
Figure S23.Mass spectrum of the natural compound ANM-A from A. maritima,related to STAR methods..

Figure S25 .
Figure S25.Mass spectrum of the silyl ether S2 obtained by micro derivatization with MSTFA after transesterification of ANM-A, related to STAR methods.

Figure S31 .
Figure S31.Mass spectrum of the natural compound XGR-F from X. grisea, related to STAR methods.

Figure S32 .
Figure S32.Mass spectrum of the natural compound XEM-B from X. maritima, related to STAR methods.

Figure S33 .
Figure S33.Mass spectra of a) the natural compound XEM-A (6) from X. maritima and b) S4, c) S5, as synthetic examples of similar ethers, related to STAR methods.

Figure S40 .
Figure S40.Mass spectrum of FQU-A from F. quadrioculata, related to STAR methods.

Figure S41 .
Figure S41.Mass spectrum of FQU-D from F. quadrioculata, related to STAR methods.

Figure S42 .
Figure S42.Mass spectrum of FQU-E from F. quadrioculata, related to STAR methods.

Figure S43 .
Figure S43.Mass spectrum of FQU-G from F. quadrioculata, related to STAR methods.

Figure S44 .
Figure S44.Mass spectrum of the FC-A from F. candida, related to STAR methods.

Figure S45 .
Figure S45.Mass spectrum of the FC-D representative for FC-B-D from F. candida, related to STAR methods.

Figure S46 .
Figure S46.Mass spectrum of the natural compound CCL-C from C. clavatus, related to STAR methods.

Figure S48 .
Figure S48.Mass spectrum of HEN-B from H. nitidus, related to STAR methods.

Figure S49 .
Figure S49.Mass spectrum of HEN-C from H. nitidus, related to STAR methods.

Figure S50 .
Figure S50.Mass spectra of a) OSA-A and b) OSA-B from O. cincta, related to STAR methods.

Figure S51 .
Figure S51.Mass spectra of the DMDS-derivatives of the natural compounds a) OSA-A and b) OSA-B from O. cincta, related to STAR methods.

Figure S52 .
Figure S52.Mass spectra of the hydrogenated derivatives of the natural compound a) OSA-A and b) OSA-B from O. cincta, related to STAR methods.

Figure S56 .
Figure S56.Biosynthetic pathway of cholesterol biosynthesis 5 .Reproduction of a Figure by Zhang et al., Evolution of the Cholesterol Biosynthesis Pathway in Animals.Mol.Biol.Evol.2019 36:2548-2556 by permission of Oxford University Press.Genes in green indicate four P450 enzymes that are not relevant to our study, related to STAR methods.